IGF-1 Linked to Breast, Colon and Prostate Cancers

New Test May Predict Prostate Cancer

Thursday, January 22, 1998

NEW YORK (Reuters) -- A new test that can predict a man's risk of prostate cancer may be on the horizon, according to new findings released Friday.

The test measures insulin-like growth factor-1 (IGF-1), a growth factor known to stimulate growth and inhibit death in normal and cancerous prostate cells. The net effect of this growth factor is to increase the likelihood of mutations in prostate cells, then to protect the mutated cells from programmed cell death, the body's natural mechanism for ridding itself of dysfunctional cells.

A team of investigators led by epidemiologist Dr. June M. Chan of Harvard School of Public Health in Boston, Massachusetts, used data collected on men enrolled in the national Physicians' Health Study to see if IGF-1 levels were linked to prostate cancer risk in humans as they are in the laboratory.

The investigators used blood samples obtained pre-diagnosis to measure IGF-1 and prostate-specific antigen (PSA) in 152 men diagnosed with prostate cancer during the study and in 152 age-matched controls. The PSA level is regularly used by physicians as an early-detection test for prostate cancer.

"Regardless of whether men had a PSA level above or below 4, which is the clinical cutoff..." for prostate cancers likely to advance if untreated, "...the results were very consistent," Chan told Reuters. The data revealed a significantly increased risk of prostate cancer in men with the highest levels of IGF-1, compared with those with the lowest levels. According to the report, men with the highest levels had a 4.3-fold increased risk of prostate cancer compared with those who had the lowest IGF-1 levels.

Though the findings have no immediate clinical implications, Chan said that her team hopes their report will "spur additional research" on the predictive value of IGF-1 in prostate cancer. According to a commentary in Science, the senior author of the study, Dr. Michael Pollak of McGill University in Montreal, Quebec, Canada, and colleagues have already "...found an equally strong association between IGF-1 levels and the risk of breast cancer, and they are now seeking links to colon cancer."

Chan told Reuters that if the link between IGF-1 and prostate cancer is confirmed, "...IGF levels could be used to help identify men who are at risk before they develop cancer." By contrast, she said that PSA levels are most useful in predicting disease progression in men already diagnosed with prostate cancer or its precursors. In addition, the findings may lead to new research into dietary or pharmaceutical interventions that can reduce IGF-1 levels, and potentially prevent the development of prostate cancer.